In general, an industrial robot includes an arm for making various motions and a head disposed at one end of the arm for mounting various tools. Furthermore, the industrial robot includes a plurality of cables disposed along the outside of the arm and connected to the head in order to supply electric power or control signals. For example, the cables include a power cable, a control cable, and a water cable.
Although the industrial robot is controlled through a plurality of the cables, the cables disturb the arm to make certain motions because the cables are disposed along the outside of the arm. In order to prevent the cables from disturbing the arm to make motions, a cable tube was used. That is, the cables disposed between the arm and the head are combined into the cable tube, and the cables are disposed along the arm with the cable tube not to disturb the operation of the robot 10 with in an operating radius of the robot 10.
The cable tube 4 of the industrial robot 1 extends and contracts according to the motion of the head 3. When the head 3 connected to the arm 2 of the industrial robot 1 is in an initial state before a rotation motion is made, the cable tube 4 is strained without being loosen. When the head 3 of the industrial robot 1 makes motions, the cable tube 4 between the arm 2 and the head 3 becomes loosen because the cable tube 4 is pulled to the head as much as a radius of the rotation motion.
After the cable tube 4 between the head 3 and the arm is pulled to the head 3, the cable tube 4 is not restored to an original state. Therefore, the cable tube 4 between the head 3 and the arm 2 becomes loosen. The loosen cable tube 4 is entangled or bended when the industrial robot 1 is operated. Therefore, the cables in the entangled or bended cable tube may be damaged.